The present invention relates to a method for formulating a photographic developer composition using rapid processing of silver halide color negative films and process conditions to optimize developed images for digital manipulation to provide color display images with desired aim tone and color reproduction and photographic developer compositions formulated therefrom.
Production of photographic color images from light sensitive materials basically consists of two processes. First, color negative images are generated by light exposure of camera speed light sensitive films, that are sometimes called xe2x80x9coriginatingxe2x80x9d elements because the images are originated therein by the film user (that is, xe2x80x9cpicture takerxe2x80x9d). These negative images are then used to generate positive images in light sensitive materials. These latter materials are sometimes known as xe2x80x9cdisplayxe2x80x9d elements and the resulting images may be known as xe2x80x9cprintsxe2x80x9d when coated on reflective supports or xe2x80x9cfilmsxe2x80x9d when coated on nonreflective supports.
The light sensitive materials are processed in automated processing machines through several steps and processing solutions to provide the necessary display images. Traditionally, this service has required a day or more to provide the customer with the desired prints. In recent years, customers have wanted faster service, and in some locations, the time to deliver this service has been reduced to within an hour. Reducing the processing time to within a few minutes is the ultimate desire in the industry. To do this, each step must be shortened.
Reduction in processing time of the xe2x80x9cdisplayxe2x80x9d elements or color photographic papers has been facilitated by a number of recent innovations, including the use of predominantly silver chloride emulsions in the elements, and various modifications in the processing solutions and conditions so that each processing step is shortened. In some processes, the total time can be reduced to less than two minutes, and even less than 90 seconds.
Color negative films generally comprise little or no silver chloride in their emulsions, and have silver bromide as the predominant silver halide. More typically, the emulsions are silver bromoiodide emulsions with silver iodide levels up to several mol percent. Such films have required these types of emulsions because emulsions containing high silver chloride have generally had insufficient light sensitivity to be used as camera speed materials although they have the advantage of being rapidly processed without major changes to the color developer solution.
To shorten the processing time, specifically the color development time, of films containing silver bromoiodide emulsions, more active color developer solutions are needed. Various attempts have been made to increase color developer activity by increasing the pH, increasing the color developing agent concentration, decreasing the halide ion concentration, or increasing temperature. However, when these changes are made, the stability of the solution and the photographic image quality are often diminished.
For example, when the development temperature is increased from the conventional 37.8xc2x0 C., and the color developer solution is held (or used) in the processing tanks for extended periods of times, silver bromoiodide elements processed with such solutions often exhibit unacceptably high density in the unexposed areas of the elements, that is unacceptably high Dmin.
Keeping of processing solutions for extended periods of time at high temperature for use in rapid high temperature color development of silver bromoiodide films has been accomplished by the use of a specific hydroxylamine antioxidant, as described in U.S. Ser. No. 08/590,241 (filed Jan. 23, 1996, by Cole).
Various methods have been proposed for overcoming problems encountered in processing high chloride silver halide emulsion-containing elements, but little has been done to address the problems for rapid processing of silver bromoiodide elements. For example, novel antioxidants have been developed to stabilize developer solutions (e.g., U.S. Pat. No. 4,897,339 of Andoh et al, U.S. Pat. No. 4,906,554 of Ishikawa et al, and U.S. Pat. No. 5,094,937 of Morimoto). High silver chloride emulsions have been doped with iridium compounds, as described in EP-A-0 488 737. Dyes have been developed to eliminate dye remnants from rapid processing as described in U.S. Pat. No. 5,153,112 of Yoshida et al. Novel color developing agents have been proposed for rapid development as described in U.S. Pat. No. 5,278,034 of Ohki et al.
All of the foregoing methods have been designed for processing high silver chloride photographic papers, and have not been shown to be effective in processing color negative silver bromoiodide films.
U.S. Pat. No. 5,344,750 (Fujimoto et al) describes a method for processing elements containing silver iodobromide emulsions that is allegedly rapid, including color development for 40-90 seconds. The potential problems of low sensitivity and high fog in rapidly developed elements is asserted to be overcome by using a color development temperature and an amount of color developing agent and bromide ion in the color developer that are determined by certain mathematical relationships. That is, the amount of color developing agent and bromide ion is considered to be related, and the development temperature and bromide ion concentration are related, both relationships being expressed in mathematical equations.
It has been found, however, that even when the relationships described in U.S. Pat. No. 5,344,750 are followed and color negative films are color developed in short times (less than 90 seconds), the color balance of the three color records cannot be maintained through a useful exposure range. By xe2x80x9ccolor balancexe2x80x9d is meant the display image, produced from a neutral exposure of a color negative image, will have a neutral color rendition throughout the useful exposure range. The color record imbalance is caused by the difficulty of getting sufficient development in the color record next to the support without forcing the topmost color record to be overdeveloped, resulting in high fog, contrast or Dmax. This color imbalance in the color records of a multilayer photographic color film cannot be corrected using conventional optical printing of the color negative onto a color display element. Thus, very short development times of the color negative films cannot readily provide negative images in the xe2x80x9coriginatingxe2x80x9d color negative film capable of providing display images having acceptable tone scale and color reproduction. This limitation is a serious obstacle to the development of imaging systems with very rapid access to the final photographic print.
U.S. Pat. No. 5,455,146 (Nishikawa et al) describes a method for forming color images in photographic elements containing silver iodobromide emulsions that is allegedly rapid and includes color development for 30-90 seconds. The potential problems of gamma imbalance are asserted to be overcome by controlling the morphology of the light sensitive silver halide emulsion grains, the thickness and swell rate of the photographic film, and the ratio of 2-equivalent color couplers to total couplers in the red-sensitive silver halide emulsion layer. However, the methods described in this patent require a color negative film to be specifically constructed with the noted features to correct gamma imbalance, but they do not correct the color imbalance produced by rapidly developing commercially available color negative films that do not have the noted features. In other words, the method of gamma correction requires a specific film and cannot be applied to any film on the market.
After a color negative film has been chemically processed in the manner described above, it can be scanned to create a digital representation of the image. The most common approach to scanning an image is to record the transmission of a light beam, point-by-point or line-by-line. In color photography, blue, green and red scanning beams are modulated by the yellow, magenta and cyan image dyes, respectively. In a variant color scanning approach, the blue, green and red scanning beams are combined into a single white scanning beam modulated by the image dyes that is read through blue, green and red filters to create separate color records. These records can then be read into any convenient memory medium (for example, an optical disk). Systems in which the image is passed through an intermediate device, such as a scanner or computer, are often referred to as xe2x80x9chybridxe2x80x9d imaging systems.
A hybrid imaging system must include a method for scanning or otherwise measuring the individual picture elements of the photographic media, which serve as input to the system, to produce image-bearing signals. In addition, the system must provide a means for transforming the image-bearing signals into an image representation or encoding that is appropriate for the particular uses of the system.
Hybrid imaging systems have numerous advantages because they are free of many of the classical constraints of photographic embodiments. For example, systematic manipulation (for example, image reversal, and hue and tone alteration) of the image information, that would be cumbersome or impossible to accomplish in a controlled manner in a photographic element, is readily achieved. The stored information can be retrieved from memory to modulate light exposures necessary to recreate the image as a photographic negative, slide or print at will. Alternatively, the image can be viewed on a video display or printed by a variety of techniques beyond the bounds of classical photography, such as electrophotography, ink jet printing, dye diffusion printing and other techniques known in the art.
U.S. Pat. No. 4,500,919 (Schreiber) describes an image reproduction system in which an electronic reader scans an original color image and converts it to electronic image-bearing signals. A computer workstation and an interactive operator interface, including a video monitor, permit an operator to edit or alter the image-bearing signals by means of displaying the image on the monitor. The workstation causes the output device to produce an inked output corresponding to the displayed image. The image representation or encoding is meant to represent the colorimetry of the image being scanned. Calibration procedures are described for transforming the image-bearing signals to an image representation or encoding so as to reproduce the colorimetry of a scanned image on the monitor and to subsequently reproduce the colorimetry of the monitor image on the inked output.
However, representation of the image recorded by the film is not necessarily the desired final image. U.S. Pat. No. 5,375,000 (Ray et al) teaches that the scanned image can be modified with a function representing the inverse of the film characteristic curve [density vs. log(exposure)] to obtain a representation of the image more closely representing the original image log(exposure). This approach could be used to restore the mismatched gammas in the negative film caused by rapid processing. However, modern color negative films are also designed to have chemical interactions (interimage) between the different color records to achieve a desired color position, and not necessarily a perfect rendition of the original scene. These interactions are dependent upon processing time and will produce color errors in a rapidly processed film. These changes in interimage cannot be corrected using conventional color correction tools but can be corrected when the image information has been transformed into a digital representation of the image density.
EP-A-0 624 028 (Giorgianni et al) describes an imaging system in which image-bearing signals are converted to a different form of image representation or encoding, representing the corresponding calorimetric values that would be required to match, in the viewing conditions of a uniquely defined reference viewing environment, the appearance of the rendered input image as that image would appear, if viewed in a specific input viewing environment. The described system allows for input from disparate types of imaging media, such as photographic negatives as well as transmission and reflection positives. The image representation or encoding of that system is meant to represent the color appearance of the image being scanned (or the rendered color appearance computed from a negative being scanned), and calibration procedures are described so as to reproduce that appearance on the monitor and on the final output device or medium.
U.S. Pat. No. 5,267,030 (Giorgianni et al) describes a method for deriving, from a scanned image, recorded color information that is substantially free of color alterations produced by the color reproduction properties of the imaging element. In this reference, the described system computationally removes the effects of media-specific signal processing as far as possible, from each input element used by the system. In addition, the chromatic interdependencies introduced by the secondary absorptions of the image-forming dyes, as measured by the responsivities of the scanning device, are also computationally removed. Use of the methods described in this reference transforms the signals measured from the imaging element to the exposures recorded from the original image.
Recently, there has been an increased interest in the use of conventional color film systems as the source of digital image files via scanning of reversal and color negative films. The chemical dye image in a color film provides several benefits to the customer that are not readily attainable in a digital camera system. For one, film as the image storage medium is human readable and therefore is hardware independent for interpretation of the image. The image can be interrogated and manipulated via numerous analog devices (e.g., printing onto color photographic paper or projecting on a screen) and digital scanning devices, to provide both soft and hard copy of the image. The image is archival if the chemical process was performed correctly and the processed film is stored under appropriate conditions. The color records of the original film are self-registered because film features multiple photosensitive layers that capture the scene image. All three colors records are recorded in high fidelity over the entire area of the image. No interpolation is required to determine missing color information, as is the case in single sensor digital capture systems employing CCD or CMOS sensors which contain only one photosensitive layer segmented with different colors. There is no spatial aliasing of the information owing to the spatially sampled signals recorded by digital sensors. The archival film dye image can be repetitively scanned many times, to give the same high fidelity image information. The image is not lost or degraded with the first scan, or subsequent scans.
In addition, there is the need for more rapid chemical processing of the film negative for rapid retrieval of the film image into a digital image file. In general, the chemical development process must give an image on the negative that is of low D-min, a reasonable contrast, and a D-max at or below 3.0 density. These attributes facilitate the digital scanning of the film negative to provide a digital image file. In addition, the light capturing capability of the film, or photographic speed cannot be compromised. Obviously, the digital image file can be further optimized via software manipulation and output to a wide variety of soft or hard copy devices.
Furthermore, it is preferred that rapid chemical development processes provide red, green and blue densitometric results that can be gamma and color adjusted by means that can include both channel independent (e.g. one-dimensional look up tables LUTs) channel interdependent (e.g. matrices) means to provide a xe2x80x9ccorrectedxe2x80x9d digital image file. Unfortunately, while gamma and color can be adjusted as described above, the more gain applied (by both channel independent and channel interdependent means) the more noise (originating in the original film and/or from the scanning process) will be amplified. Therefore, it is desirable to optimize the photo process to produce results that minimize the subsequent amplification required to restore the rapid chemical developed film to film that was photoprocessed through conventional processes.
Recent patents by Cole and Bohan (U.S. Pat. No. 5,804,356) and also Bohan, Buchanan, and Szajewski (U.S. Pat. Nos. 5,693,379 and 5,840,470) which are herein incorporated by reference in their entirety, respectively provide possible avenues to obtaining digital image files from scanned, rapidly developed, film negatives. U.S. Pat. No. 5,804,356 is deficient in that it provides a such wide range of processing chemical concentrations and processing conditions such that a person of ordinary skill in the art would not be led to those concentrations and conditions that produce images optimized for digital scanning and subsequent manipulation.
All three of the above mentioned patents fail to provide a method to optimize the chemical developer to provide the best dye image (i.e. image requiring the minimum amount of amplification).
The prior art lacks a method to rapidly chemically process a color film that provides a superior dye image for digital scanning. Such a method would include formation of a dye image on the film that is of low D-min value and suitable contrast and D-max value, which would facilitate the digital scanning of the film negative to provide a digital image file. Such a method would provide a means for designing the chemical process to minimize the need for amplification of the digitally scanned image, while insuring that the chemical process is designed to maintain the photographic speed of the film. Most importantly, there is a need for a quantitative method to evaluate the rapid developer/process for the attainment of an optimal digital image file. Thus, there remains a need for a process for providing color display images from images originated in commercially available silver bromoiodide films which require minimal correcting of color imbalances that occur in the color records from the rapidity of the film processing.
The problems described above have been overcome with a method for deriving a color negative film developer composition and processing conditions for developing a photographic image which is optimized for subsequent digital scanning and digital image file manipulation and which allows for optimum rapid development processing of the film. The method includes identifying at least one independent variable that has a first order effect on the density of at least one of the red, green, and blue dye images of the developed image. A range of values is selected for the independent variables identified. Then an experimental design is formulated that includes desired independent variables over the desired range of values. The experiment is then performed to obtain statistically significant values for the desired dependent variables. The values are applied to a mathematical model capable of providing a formula for optimizing responses to the dependent variables. The formula is used to identify desired optimal developer composition and processing conditions resulting in a developed image in which the subsequent required digital scanning and digital image file manipulation is reduced.
In this manner, a color negative film developer composition, suitable for rapid development processing and optimized for subsequent digital scanning and digital image file manipulation, can be prepared.
The present invention also provides a method for providing a color display image including developing an imagewise exposed color silver halide negative working film having at least two color records, with a color developer solution composition and under development process conditions derived in accordance with the above method. The developed film is scanned to form density representative signals for the at least two color records. Then the density representative signals are digitally manipulated to correct either or both interimage interaction and gamma mismatches among the at least two color records to produce a digital record providing a display image having desired aim color and tone scale reproduction, such that the amount of digital manipulation is minimized. The present invention is also directed to a color or monotone image prepared from this digital record.